The links below may point to other sensor versions (SHT41, or SHT45). Double-check that you are buying the specific model you need. Looking for another version of the SHT4X series? You can also buy the SHT41 or SHT45 versions.
Aliexpress - SHT40: I2C Temperature and Humidity Sensor
$3.98
Aliexpress
Amazon.de - SHT40 or SHT41 or SHT45: I2C Temperature and Humidity Sensor
€6.09
Amazon.de
Amazon.co.uk - SHT40: I2C Temperature and Humidity Sensor
£6.12
Amazon.co.uk
Amazon.com - SHT40: I2C Temperature and Humidity Sensor
$8.49
Amazon.com
eBay - SHT40: I2C Temperature and Humidity Sensor
$10.91
eBay
Amazon.es - SHT40: I2C Temperature and Humidity Sensor
€16.11
Amazon.es